The invention relates to ceramic moldings containing finely crystalline cordierite, a method for their production, and their use.
Cordierite (2Al.sub.2 O.sub.3.2MgO.5 SiO.sub.2) is commonly made by devitrifying a glass composition of the appropriate nominal formulation, or by sintering vitreous powders (with simultaneous devitrification) or precrystallized (ceramicized) powders. The strength and viscosity (approximately &lt;150 MPa and &lt;1.5 MPa.sqroot.m) and the modulus of elasticity (&lt;100 GPa) of such materials is of course low. However, on account of the low thermal coefficient of expansion (&lt;1.10.sup.-6 /K), the low dielectric constant and low conductivity, bodies molded from cordierite would be very suitable as dielectrics, e.g., for integrated-circuit substrates, and as heat blocking components, e.g., for use in the thermally stressed areas of heat engines, such as conventional piston engines, for example.
It is therefore the object of the present invention to offer cordierite moldings which, in addition to good dielectric and heat blocking properties, will also have good mechanical properties. This object is achieved by ceramic moldings according to the invention.